1. Field of the Invention
The present invention relates to a fish processing and preserving method in which smoke-dry components are dissolved in a solution to thereby make it possible to realize a smoke-dried and frozen product such as a cut fish, a yellowtail and an amberjack which are a medium size fish and a tuna fish which is a large size fish with high quality and high freshness.
2. Description of the Related Art
For example, a muscle property of a tuna fish is a reddish muscle fish as a whole (in which myoglobin protein pigments are dispersed in a whole body) unlike a yellowtail and other white muscle fish. If a tuna having a reddish muscle is preserved under a normal freezing and preserving condition under about −20° C., a brown change effect (methemoglobin change) spreads to a whole body muscle property as time lapses, as a result of which the color of the muscle turns almost brown or black after thawing. Although there is no problem at all in a nutritive value aspect or a sanitary or healthy aspect, the muscle is not suitable for a “sashimi” material (raw fish material) that is eaten through eyes. Accordingly, almost all the tuna fish which is landed is used for canned food.
A patent was obtained by Taiyo Gyogyo Co., Ltd (now Maruha Co., Ltd) in 1961 for a brown change effect (methemoglobin change) preventing method during freeze preserving. At that time it was a common sense in this business field that the color of the fish muscle turned black and brown at about 24° C. but it was found that when the temperature was further lowered down to −65° C., the fresh reddish color might be kept for a long period of time. Thus, a basic technology for eating a frozen tuna under the condition of “sashimi” was established. However, the color tone of the tuna muscle is very delicate and subject to change and it is impossible to suppress the change in the processed condition of fillet (loins) for a long period of time even at −60° C. For this reason, now, all the frozen and preserved tuna is handled in the form of a “round” product which is covered by a surface skin which is a natural protective film.
For this reason, in this business field, there is a demand for removing non-edible part which corresponds to two-thirds of the overall weight of the tuna to reduce the transporting cost but this has not been attained due to the above-described situation.
The tuna product was born as a frozen food because the tuna itself was expensive and Japanese stick the color tone of “sashimi”. However, in order to handle the food under such a low temperature, it is a premise to consume a large amount of fossil energy (petroleum) for a freezing and preserving period. In Japan, recently, a super low temperature circulation system has been established and almost all the Japanese sashimi tuna is circulated through this circulation system. Recently, there is a demand of protection of circumstances and saving energy and some people are of the opinion that this system goes against the demand of saving energy, which is supported by the scientific society or the business field.